Petriolo is a comune (municipality) in the Province of Macerata in the Italian region Marche, located about south of Ancona and about south of Macerata. As of 31 December 2004, it had a population of 2,063 and an area of .
Petriolo borders the following municipalities: Corridonia, Loro Piceno, Mogliano, Tolentino, Urbisaglia.
Among the churches in the town are: